Neurons and How They Work

Underneath the newfangled cortex, the brain stem, the limbic system... and the basal ganglia date back to the mastodons, the dinosaurs... ...and the first amphibians. In humans, the old parts of the brain oversee emotion and help build memories. They control heart rate and breathing. They also form intimate connections with the new brain: the cortex. Though less than a quarter inch thick, the cortex is the brain’s crowning glory. Among its roles, the cortex is our reality check. It filters and orders the outside world for us and allows us to see, touch, hear, and speak. The cortex is also the human thinking cap. all our plans, thoughts, and ideas originate in this layer. The cortex is packed with nerve cells; about two thirds of all our neurons operate here. A piece of cortex tissue no larger than a pinhead can house 30,000 of these cells. Each neuron has the job to communicate with other neurons. The brain works by forming networks among these cells. The long spiny branches of the networks create a neuro-forest of astounding intricacy. Neurons use these communication lines to talk to each other with electric and chemical signals. Here, under microscope are two neurons linking up. Though it may look like they fuse together, neurons don’t actually touch each other. A closer look reveals that the tiny gap, called the synapse, separates their branches. This is where a message passes from one neuron to the next.